Treatment of Pertechnetate (TcO4-)-Contaminated Groundwater

 

 

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Breakthrough of pertechnetate (TcO4-) on a bifunctional RO-02-119 resin column in a field experiment at the Paducah Gaseous Diffusion Plant site, Kevil , Kentucky .  The influent groundwater contained ~0.07 ppb Tc.

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Less than 3% TcO4- breakthrough observed after treatment of ~700,000 bed volumes of groundwater.

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Pertechnetate (TcO4-)    an analog to perchlorate (ClO4-).

This study evaluated a new class of bifunctional anion-exchange resins developed at the Oak Ridge National Laboratory for removing pertechnetate (TcO4-) from contaminated groundwater.  Both laboratory-column and field flow-through experiments were performed, and results indicated that superior performance of the bifunctional resins has been achieved through the use of two quaternary ammonium groups, one having long chains (trihexylamine) for higher selectivity for poorly hydrated large anions and one having shorter chains (triethylamine) for enhanced kinetics and exchange capacity.  Field results indicated that the bifunctional resin performed much better than one of the best commercial monofunctional anion-exchange resins (e.g., Purolite A-520E) with respect to the removal of TcO4- from contaminated groundwater (with improved selectivity and sorption kinetics).  Less than 3% of TcO4- breakthrough was observed after ~700,000 bed volumes (BV) of contaminated groundwater had been treated by the bifunctional resin column at the U.S. Department of Energy's Paducah Gaseous Diffusion Plant site.  The results demonstrate that the new resin is particularly effective in removing low levels of TcO4- (e.g., at influent concentration of ~0.07 mg/L or ~0.7 nmol/L Tc), and a cost saving may be realized by using the bifunctional resins for the treatment of large quantities of contaminated groundwater because of its increased selectivity, treatment efficiency, and longevity.  The new resin may also be applied for the efficient treatment of other poorly hydrated large anions such as perchlorate (ClO4-) from contaminated groundwater or surface water.

 

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